1. Field of the Invention
The present invention relates to a transmitting device, a receiving device, a packet transmission system and a packet signal transmission method for conducting a packet transmission. More particularly, this invention relates to the above-mentioned devices and methods which enable efficient packet data compression.
2. Description of the Related Art
With the distribution of computers, data communication has become common. A packet transmission method is often used for an efficient data communication. A packet is a data package which is exchanged between devices through a data communication link. A packet generally includes data and headers. A header is, for example, address information which is necessary for a correct transmission of data.
There are following prior arts concerning a packet transmission:
"Transmission of Information Sequence Number in Packet Data Transmission System" described in the official gazette of the Japanese Patent Laid-Open (Kokai) Publication No. SHO 61-161847 is a transmission method for including sequence numbers in a packet information field and for acknowledging the information by returning the number of the received information. By this method, an acknowledgment status is transmitted for n units of information packets which have been received prior to the information packet then received. "Method of Receiving Data Packet of at Least One Packet by Receiving Device" described in the official gazette of the Japanese Patent Laid-Open (Kokai) Publication No. HEI 6-188912 memorizes, upon receiving data packets including a first packet, which may optionally include a direction that a second packet is to be subsequently transmitted, and an optional second data packet, information which indicates the data packet within the memory, and accepts data packet information according to whether or not there is a direction.
"Packet Signal Selecting Device and Movement Switching Center" described in the official gazette of the Japanese Patent Laid-Open (Kokai) Publication No. HEI 6-261074 chooses a single packet by comparing a plurality of packets coming in from a plurality of transmission paths.
"Data Transfer Method and Data Transmitting Device and Restoring Device" described in the official gazette of the Japanese Patent Laid-Open (Kokai) Publication No. HEI 5-35624 is a data transfer method for transmitting data through a plurality of channels by dividing the data into a plurality of packets, and for restoring the data into the original data.
If a Ethernet between a terminal and a hub is replaced with a wireless system, point-to-point packet communication will be conducted, and the packet of the Ethernet will be transferred without any change through a wireless channel. In this case, since only the packets from or to a specific terminal are basically transmitted, the address portions in the control field of the Ethernet are occasionally the same. In other words, an address method of such transmission are inefficient and redundant. The prior arts listed above could not solve the above-described problems.